The field of art to which this invention relates is aqueous dispersions of synthetic polymers obtained by polymerizing ethylenically unsaturated monomers. In particular, the field of art of this invention is vinyl acetate copolymer dispersions having improved adhesion properties when formulated into protective coatings.
Aqueous dispersions containing homopolymers and copolymers of vinyl acetate have been known for many years. Films of these polymers normally exhibit excellent appearance and durability. However, when pigmented and formed into paints, these compositions do not generally have good adhesion properties, particularly wet adhesion and blister resistance.
While many monomers and processes have been investigated for improving the adhesion of these coatings, no completely satisfactory method has yet been found. Many prior art adhesion improving monomers were either too expensive or were of limited usefullness due to deficiencies in other paint properties brought about by their use. In addition, many of the prior art processes for preparing paints having improved adhesion are time-consuming and require expensive modifications in processing equipment.
These and other difficulties are overcome by preparing the aqueous dispersions of the instant invention, which exhibit generally improved adhesion properties over prior art dispersions which are not so modified.